Shiva Purana
अर्घमादाय देहस्थं सव्यनासापुटेन च ॥ कृष्णवर्णेन बाह्यस्थं भावयेच्च शिलागतम् ॥ २० ॥
Taking off the dark-complexioned sin of the body through the left nostril and that outside, he shall conceive it as gone to the rock.
english translation
arghamAdAya dehasthaM savyanAsApuTena ca ॥ kRSNavarNena bAhyasthaM bhAvayecca zilAgatam ॥ 20 ॥
hk transliteration by Sanscript